Conventionally, there is known an evaporated fuel processing device (so-called evaporation purge system) in which evaporated fuel generated in a fuel tank is adsorbed by a canister once, and purge gas containing the evaporated fuel adsorbed by the canister is purged to an intake passage of an engine in response to a purge demand. Additionally, a technology of determining anomaly of such an evaporated fuel processing device is also known (refer to Patent Document 1, for example). This Patent Document 1 discloses a technology of determining that a purge valve is anomalous in a case where change of canister internal pressure during supply of purge gas to an intake passage is small (that is, during purge execution).